Biometrics and Cryptography -- Introduction CPSC 4600/5600 Biometric and Cryptography University of Tennessee at Chattanooga
Who are you? ? 2
How are people identified? n People’s identity are verified and identified by three basic means: – Something they have (identity document or token) – Something they know (password, PIN) – Something they are (human body such as fingerprint or iris). n The strongest authentication involves a combination of all three. 3
Person Identification n n Identifying fellow human beings has been crucial to the fabric of human society In the early days of civilization, people lived in small communities and everyone knew each other With the population growth and increase in mobility, we started relying on documents and secrets to establish identity Person identification is now an integral part of the infrastructure needed for diverse business sectors such as banking, border control, law enforcement. 4
Automatic Identification Different means of automatic identification: n Possession-based (credit card, smart card) – “something that you have” n Knowledge-based (password, PIN) – “something that you know” n Biometrics-based (biometric identifier) – “something about or produced by your physical make-up” 5
Problems with Possession- or Knowledge-based Approaches n n Card may be lost, stolen or forgotten – Password or PIN may be forgotten or guessed by the imposters ~25% of people seem to write their PIN on their ATM card Estimates of annual identity fraud: – More than 11 million adults became victims of identity fraud in 2011 (Javelin Strategy & Research, 2012 Identity Fraud Report) – $1 billion in fraudulent cellular phone use – $3 billion in ATM withdrawals The traditional approaches are unable to differentiate between an authorized person and an impostor 6
Identification Problems n Identity Theft: Identity thieves steal PIN (e. g. , date of birth) to open credit card accounts, withdraw money from accounts and take out loans $37 billion identity thefts in U. S. in 2010; Surrogate representations of identity such as passwords and ID cards no longer suffice 7
What are Biometrics? n n n Biometrics – science, which deals with the automated recognition of individuals (or plants/animals) based on biological and behavioral characteristics Biometry – mathematical and statistical analysis of biological data Biometric system – a pattern recognition system that recognizes a person by determining the authenticity of a specific biological and/or behavioral characteristic (biometric) Anthropometry–measurement techniques of human body and its specific parts Forensic (judicial) anthropometry–identification of criminals by these measurement techniques 8
Why Biometrics 9
Why Biometrics? 10
Mentioning the Obvious 11
Requirements for an Ideal Biometric Identifier 1. Universality – Every person should have the biometric characteristic 2. Uniqueness – No two persons should be the same in terms of the biometric characteristic 3. Performance – The biometric characteristic should be invariant over time 4. Collectability – The biometric characteristic should be measurable with some (practical) sensing device 5. Acceptability – One would want to minimize the objections of the users to the measuring/collection of the biometric 12
Identifiable Biometric Characteristics n Biological traces – DNA (Deoxyribo. Nucleic Acid), blood, saliva, etc. n Biological (physiological) characteristics – fingerprints, eye irises and retinas, hand palms and geometry, and facial geometry n Behavioral characteristics – dynamic signature, gait, keystroke dynamics, lip motion n Combined – voice 13
Biometrics is Not New!! n n n Bertillon system (1882) took a subject's photograph, and recorded height, the length of one foot, an arm and index finger Galton/Henry system of fingerprint classification adopted by Scotland Yard in 1900 FBI set up a fingerprint identification division in 1924 AFIS installed in 1965 with a database of 810, 000 fingerprints First face recognition paper published in 1971 (Goldstein et al. ) FBI installed IAFIS in ~2000 with a database of 47 million 10 prints; average of 50, 000 searches per day; ~15% of searches are in lights out mode; 2 hour response time for criminal search Emphasis now is to automatically perform reliable person identification in unattended mode, often remotely (or at a distance) 14
n Biometrics – A biometric authentication system uses the physiological (fingerprints, face, hand geometry, iris) and/or behavioral traits (voice, signature, keystroke dynamics) of an individual to identify a person or to verify a claimed identity. 15
Comparison of Biometric Techniques 16
Key Biometric Terms and Process 17
What is Biometric? Biometrics is the automated use of physiological or behavioral characteristics to determine or verify identity. n Automated use means using computers or machines, rather than human beings, to verify or determine physiological or behavioral characteristics. n 18
Biometrics n 2 Categories of Biometrics – Physiological – also known as static biometrics: Biometrics based on data derived from the measurement of a part of a person’s anatomy. For example, fingerprints and iris patterns, as well as facial features, hand geometry and retinal blood vessels – Behavioral – biometrics based on data derived from measurement of an action performed by a person, and distinctively incorporating time as a metric, that is, the measured action. For example, voice (speaker verification) 19
Using Biometrics Enrollment, Verification Recognition 20
Using Biometrics n n Process flow includes enrollment, and verification/identification. Enrollment – Person entered into the database – Biometric data provided by a user is converted into a template. – Templates are stored in a biometric systems for the purpose of subsequent comparison. 21
Verification versus Identification n Verification: Am I who I claim to be? – One to one comparison – Verification can confirm or deny the specific identification claim of a person. 22
Identification versus Verification n Identification: Who am I? – One to many comparison – can determine the identity of a person from a biometric database without that person first claiming an identity. 23
Discussion: Verification and Identification n n Verification system answers the question: “Am I who I claim to be? ” The answer returned by the system is match or no match. Identification systems answers the question: “Who am I” The answer returned by the system is an identity such as a name or ID number. 24
Discussion: Verification and Identification 25
When are verification and identification appropriate? n n n PC and Network Security -- verification Access to buildings and rooms – either verification (predominant) or identification Large-scale public benefit programs – identification Verification systems are generally faster and more accurate than identification systems. However, verification systems cannot determine whether a given person is present in a database more than once. 26
When are verification and identification appropriate? n n Identification system requires more computational power than verification systems, and there are more opportunities for an identification system to err. As a rule, verification systems are deployed when identification simply does not make sense (to eliminate duplicate enrollment, for instance. ) 27
Total Biometrics Market 28
Different Biometrics 29
Physiological and Behavioral Characteristics n n Physiological or behavioral characteristics are distinctive, which provide basic measurement of biometrics. Physiological biometrics are based on direct measurements of a part of the human body, such as finger-scan, facial-scan, iris-scan, hand-scan, and retina-scan. Behavioral biometrics are based on measurements and data derived from an action and therefore indirectly measure characteristics of the human body, such as voice-scan and signature-scan. The element of time is essential to behavioral biometrics. 30
DNA (Deoxyribo Nucleic Acid) The Ultimate Biometric n n One-dimensional unique code for one’s individuality, but identical twins have identical DNA patterns Issues limiting the utility of DNA – – Contamination Access Automatic real-time recognition issues Privacy issues: information about susceptibilities of a person to certain diseases could be gained from the DNA pattern 31
Behavioral vs Physical Traits n Physical Characteristics – – – – n Iris Retina Vein Pattern Hand Geometry Face Fingerprint Ear shape – – Keystroke dynamics Signature dynamics Walking Gait Voice Behavioral Characteristics 32
Fingerprints 33
Fingerprint Features 34
Iris Recognition: Eye 35
Iris Code 36
National Geographic 1984 and 2002 37
Retina Every eye has its own totally unique pattern of blood vessels. 38
Face Recognition: Correlation 39
Face Recognition: 3 D 40
Hand 41
Palm 42
Vein 43
Ear 44
Market Share 45
Biometric Applications 46
Biometric Application n Biometric technology is used for many applications – Providing time and attendance functionality for a small company – Ensuring the integrity of a 10 million-person voter registration database n The benefit of using biometrics include increased security, increased convenience, reduced fraud or delivery of enhanced services. 47
UCSD Biometric Soda Machine 48
*As part of the enhanced procedures, most visitors traveling on visas will have two fingerprints scanned by an inkless device and a digital photograph taken. All of the data and information is then used to assist the border inspector in determining whether or not to admit the traveler. These enhanced procedures will add only seconds to the visitor’s overall processing time. 49
National Biometric ID Cards U. K. to consider national biometric ID cards, database By Laura Rohde, COMPUTERWORLD (Nov 29, 2003)The U. K. government is set to consider legislation next year for the establishment of compulsory biometric identity cards and a central database of all U. K. subjects, it was announced by the government this week. The information that the government is considering for inclusion on the card includes personal details such as a person's home address and telephone number, his National Insurance number (the equivalent of the U. S. Social Security number), medical information and criminal convictions, as well as the biometric information, most likely in the form of an iris, fingerprint or palm print scan. 50
Access Control 51
Did You Vote? 52
Applications n Video Surveillance (On-line or off-line) 53
Fingerprint System at Gas Stations “Galp Energia SGPS SA of Lisbon won the technology innovation award for developing a payment system in which gasoline-station customers can settle their bills simply by pressing a thumb against a glass pad. Scanning technology identifies the thumbprint and sends the customer's identification information into Galp's back-office system for payment authorization. ” THE WALL STREET JOURNAL, November 15, 2004 54
Using Iris Scans to Unlock Hotel Rooms The Nine Zero hotel in Boston just installed a new system which uses digital photos of the irises of employees, vendors and VIP guests to admit them to certain areas, the same system used in high-security areas at airports such as New York's JFK. 55
Fingerprint System at Border Crossings “Foreigners entering the United State in three cities, including Port Huron, were fingerprinted, photographed and subjected to background checks on Monday in a test of a program that will eventually be extended to every land border crossing nationwide. ” Lansing State Journal, Nov. 16, 2004 56
New Passports The new passports have an embedded contactless (ISO 14443) “smart-card” chip that stores personal information and a biometric template. Two problems: reliability and privacy 57
Want to Charge It? You'll Have to Talk to Your Credit Card Beepcard, a company in California, has designed a credit card that works only when it recognizes the voice of its rightful owner. Enclosed in the card is a tiny microphone, a loudspeaker and a speech recognition chip that compares the spoken password with a recorded sample. If the voices match, the card emits a set of beeps that authorize a transaction over the telephone or the Internet. If the voices do not match, the card will not beep. The system tolerates some variations in voice to accommodate cold or background noise. But it might not work if there is a blaring music in the background. 58
Biometrics for Personalization n Automatic personalization of vehicle settings: – – – n Seat position Steering wheel position Mirror positions Lighting Radio station preferences Climate control settings URLs at your fingertips 59
Key Terms 60
Template (1) n n n A template is a small file derived from the distinctive features of a user’s biometric data, used to perform biometric matches. Templates, is calculated during enrollment or verification phase. The template be understood as a compact representation of the collected feature data, where useless or redundant information is discarded. Biometric systems store and compare biometric templates, NOT biometric data. 61
Template (2) n n n Most template occupy less than 1 kilobyte, and some of them are as small as 9 bytes; size of template differs from vendor to vendor. Templates are proprietary to each vendor and each technology, and there is no common biometric template format. This is beneficial from a privacy perspective, but the lack of interoperability deterred some would-be users. 62
Templates n n n Biometric data CAN NOT be reconstructed from biometric templates. Templates are extractions of distinctive features and not adequate to reconstruct the full biometric image or data. Unique templates are generated every time a user presents biometric data. For example, two immediately successive placement of a finger on a biometric device generate entirely different templates which are processed by vendor’s algorithm and recognizable as being from the same person, but are not identical. 63
Biometric Templates versus Identifiable Biometric Data Depending on when they are generated, templates can be referred to as enrollment templates or match templates. 64
The two stages of a biometric system 65
Enrollment and Template Creation (1) n n n Enrollment is a process to acquire, assess, process, and store user’s biometric data in the form of a template. Stored templates are used for subsequent verification and identification. Quality enrollment is a critical factor in the long-term accuracy of biometric system. 66
Enrollment and Template Creation (2) Presentation is the process by which a user provides biometric data to an acquisition device – the hardware used to collect biometric data. n For example, looking in the direction of a camera, placing a finger on a platen, or reciting a passphrase. n 67
Enrollment and Template Creation (3) n n n Biometric data are converted to templates through feature extraction. Feature extraction is the automated process of locating and encoding distinctive characteristics from biometric data in order to generate a template. Feature extraction removes noises and unwanted data, and digitize biometric traits. 68
Enrollment and Template Creation (4) n n A user may need to present biometric data several times in order to enroll. Enrollment score or quality score indicates the enrollment attempt is successful or not. If the user’s biometric data contains highly distinctive features or an abundance of features, there will likely be a high enrollment score. Vendor’s feature extraction processes are generally patented and are always held secret. 69
How Biometric Matching Works Verification/Identification template is compared with enrollment templates. n The comparison renders a score, or confident value. n The score is compared with threshold. n If the score exceeds the threshold, the comparison is a match, non-match otherwise. n 70
Biometric Algorithm n A biometric algorithm is a recipe for turning raw data - like physical traits – into a digital representation in the form of a template. It also allows the matching of an enrolled template with a new template just created for verifying an identity, called the live template. 71
Biometric Matching n n n Matching is the comparison of enrolled biometric templates with a new template just created for verification to determine their degree of similarity or correlation. In verification systems, a verification template is matched against a user’s enrollment template or templates (multiple). In Identification systems, the verification template is matched against dozens, thousands, even millions of enrollment templates. 72
Biometric Matching – Scoring n n Biometric systems utilize proprietary algorithms to process templates and generate scores. Some of them use a scale of 1 to 100, others use a scale of -1 to 1. Traditional authentication methods such as password offer on a yes’/no response. In biometric system, there is no 100 percent correlation between enrollment and verification templates. 73
Biometric Matching --Threshold n n A threshold is a predefined number, which establishes the degree of correlation necessary for a comparison to be deemed a match. Thresholds can vary from user to user, from transaction to transaction, and from verification to verification attempt. System can be either highly secure for valuable transaction or less secure for low-value transaction, depending on their threshold settings. Traditional authentication can not offer such flexibility. 74
Biometric Matching -- Decision The result of the comparison between the score and the threshold is a decision. n The decisions a biometric system can make include match, non-match, and inconclusive. n 75
Biometric Matching: Process Flow n n The user submits a sample (biometric data) via an acquisition device (for example, a scanner or camera) This biometric is then processed to extract information about distinctive features to create a trial template or verification template Templates are large number sequences. The trial/match template is the user’s “password. ” Trial/match template is compared against the reference template stored in biometric database. 76
Overview of Biometrics Biometric Acquisition Device Sample Feature Extracted Iris Infrared-enabled video camera, PC camera Black and white iris image Furrows and striations of iris Fingerprint Desktop peripheral, PC card, mouse chip or reader embedded in keyboard Fingerprint image (optical, silicon, ultrasound or touchless) Location and direction of ridge endings and bifurcations on fingerprint, minutiae Voice Microphone, telephone Voice Recording Frequency, cadence and duration of vocal pattern Signature Tablet, Motion-sensitive stylus Image of Signature and record of related dynamics measurement Speed, stroke order, pressure and appearance of signature Face Video Camera, PC camera, singleimage camera Facial image (optical or thermal) Relative position and shape of nose, position of cheekbones Hand Proprietary Wall-mounted unit 3 -D image of top and sides of hand Height and width of bones and joints in hands and fingers Retina Proprietary desktop or wall mountable unit Retina Image Blood vessel patterns and retina 77
Strengths, Weaknesses and Usability of Biometrics Biometric Strengths Weakness Usability Iris Very stable over time Uniqueness Potential user resistance Requires user training Dependant on a single vendor’s technology Fingerprint Most mature biometric technology Accepted reliability Many vendors Small template (less than 500 bytes) Small sensors that can be built into mice, keyboards or portable devices Physical contact required (a problem in some cultures) Association with criminal justice Vendor incompatibility Hampered by temporary physical injury Most proven over time Temperature stable Optical Large physical size Latent prints coating erodes with age Durability unproven Information security access control, especially for Federal Institutions and government agencies Physical access control (FIs and government) Kiosks (ATMs and airline tickets) IS access control Physical access control Automotive 78
Strengths, Weaknesses and Usability of Biometrics Strengths Weakness Silicon Small physical size Cost is declining Requires careful enrollment Unproven in sub optimal conditions Ultrasound Most accurate in sub optimal conditions New technology, few implementations Unproven long term performance Good user acceptance Low training Microphone can be built into PC or mobile device Voice Signatures High user acceptance Minimal training Usability Unstable over time Changes with time, illness stress or injury Different microphones generate different samples Large template unsuitable for recognition Mobile phones Telephone banking and other automated call centers Unstable over time Occasional erratic variability Changes with illness, stress or injury Enrollment takes times Portable devices with stylus input Applications where a “wet signature” ordinarily would be used. 79
Strengths, Weaknesses and Usability of Biometrics Strengths Weakness Usability Face Cannot distinguish identical siblings Religious or cultural prohibitions Physical access control Physical size of acquisition device Physical contact required Juvenile finger growth Hampered by temporary physical injury Physical access control Time and attendance Requires user training and cooperation High user resistance Slow read time Dependent on a single vendor’s technology Universally present Hand Retina Small template (approximately 10 bytes) Low failure to enroll rate Unaffected by skin condition Stable over time Uniqueness IS access control, especially for high security government agencies Physical access control (same as IS access control) 80
Accuracy in Biometric Systems
How to Evaluate Performance of a Specific Technology? False acceptance rate n False rejection rate n Failure-to-enroll rate n No single metric indicates how well a biometric system or device performs: Analysis of all three metrics is necessary to assess the performance of a specific technology. n 82
False Acceptance Rate n n If John Smith enters Jane Doe’s username or ID, presents biometric data, and successfully matching as Jane Doe. This is classified as false acceptance. The probability of this happening is referred to as false acceptance rate (FAR)[ stated as: percentage, fraction] This is because two people have similar enough biometric characteristics – a fingerprint, a voice, or a face – that the system finds a high degree of correlation between the users’ template. 83
False Acceptance Rate n n FAR can be reduced by adjusting the thresholds but the false rejection rate will increase. A system with a false acceptance rate of 0 percent, but false rejection rate of 50 percent, is secure but unusable. False acceptance rate is the most critical accuracy metric because an imposter break-in will certainly be a more attention-getting event than other failings of a biometric system. The most important false match metric in real-world deployments is the system false match rate. 84
False Rejection Rate n n n If John Smith enters his username or ID, presents his biometric data to a biometric system, and fails to match. This is classified as false rejection. The probability of this happening is the false rejection rate (FRR). This can be attributed to changes in user’s biometric data, changes in how a user presents biometric data, and changes in the environment in which data is presented. High FRR will result in lost productivity, frustrated users, and an increased burden on help desk or support personnel. 85
Reasons of FRR n Changes in user’s biometric data – Voice-scan system is influenced by sore throats – Facial-scan system is affected by changes in weight – Fingerprint changes over time, scars, aging and general wear. 86
Acceptance and Rejections n If someone else is trying to verify as you, the system would try to match the two templates. – If the two templates were to match – this is classified as false acceptance. – If your authentication template fails to match your enrolled template, then this is referred to as a false rejection. – If you are new and fail to enroll to a biometric system, this is called – failure to enroll (FTE). 87
Accuracy Rates n Single False Acceptance Rate vs. System False Acceptance Rate – If the FAR is 1/10, 000 but you have 10, 000 templates on file — odds of a match are very high n Ability to Verify (ATV) rate: – % of user population that can be verified – ATV = (1 -FTE)(1 -FRR) 88
Legitimate users get accepted. • Tradeoff b/w true acceptance rate and false rejection rate. True acceptance rate Receiver operating characteristic (ROC) Curve • Cost/benefit analysis of decision making. Legitimate users get rejected. False rejection rate 89
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